In potato processing operations such as used in the dehydration of potatoes, water flows through various cookers, precookers and blanchers serving to minimize bacterial, taste and odor problems. The overflow or effluent water from such processing operations is called potato wastewater or potato water. Such potato wastewater is difficult to filter due to dissolved starch which tends to block screens in the filtration equipment. Various regulatory agencies are instituting stricter standards for the disposal of such wastewater. Accordingly, there is a need to reduce the potato solids in such wastewater, and to recover the solids as a usable byproduct.
It is an objective of the invention to provide a method for treating potato wastewater. The method comprises the following steps:
(a) pretreating a potato wastewater stream including suspended and dissolved solids with an alpha amylase enzyme to hydrolyze starch in the wastewater,
(b) ultra-filtering the enzyme-treated wastewater from step (a) to filter and remove a portion of the suspended solids in a first concentrate stream separated from the wastewater, and
(c) reverse osmosis-filtering the ultra-filtered wastewater from step (b) to remove at least about 70% of the wastewater dissolved and suspended solids in a second concentrate stream.